The thyroid and immune system have an interactive relationship. This means that thyroid issues can affect the immune system, and immune system issues can affect the thyroid.
Hyperthyroidism often occurs due to an autoimmune disease, but regardless of its cause, it may affect immune function. Researchers know that thyroid function may affect the immune system, but exactly how remains unclear.
Instead, the effects may be more subtle.
Read on to learn about the connection between hyperthyroidism and the immune system.

The
In the case of Graves’ disease, the body attacks tissue in the thyroid, causing an overproduction of thyroid hormone.
Researchers do not know exactly what triggers the immune system to attack the thyroid in Graves’ disease.
This means that Graves’ disease may be a sign of, but not necessarily a cause of, a weak immune system.
Additionally, researchers believe that the thyroid and immune system communicate with each other, so an issue with one may cause an issue with the other. 2019 research on rats with hyperthyroidism suggests that dysregulated thyroid hormone may affect the immune system. However, this does not mean the same is true in humans.
Some doctors
More research is necessary to understand the precise effects hyperthyroidism has on the immune system.
While some studies suggest the thyroid affects the immune system, others undermine that claim. For example, in a
While the study found a link between hyperthyroidism and an increased risk of death from breast cancer, it did not increase the risk of dying from infections. The study did not show a direct causal link between the two — this means it did not find that having hyperthyroidism caused death from breast cancer.
Environmental factors, including those that affect the immune system, sometimes trigger Graves’ disease.
They include:
Graves’ disease does not directly weaken the immune system. However, a
A 2019 review highlights that people with Graves’ disease may have higher levels of a type of interleukin, an inflammatory chemical the immune system secretes. They may also have lower levels of certain immune system cells.
Researchers do not yet know the effects these changes may have, but data suggests that Graves’ disease correlates with changes in the immune system.
Hyperthyroidism tends to speed up many functions in the body. As a result, a person may have some or all of the
- often feeling hot
- heat intolerance
- racing heart or heart palpitations
- difficulty sleeping
- feeling anxious, jittery, or keyed up
- an increase in appetite along with weight loss
A person can have mild or no symptoms and still have hyperthyroidism. The only way to definitively diagnose it is to test for thyroid hormone levels in the blood.
Treatment for hyperthyroidism depends on the severity of the person’s symptoms. The primary treatment
- Symptom medication: Medications such as beta-blockers can control symptoms of hyperthyroidism.
- Thyroid medication: Anti-thyroid drugs slow the overproduction of thyroid hormone. Some commonly prescribed
options include methimazole and carbimazole. - Removing the thyroid: If symptoms are severe, doctors may recommend removing the thyroid. This usually means a person will have to take replacement thyroid hormone for the rest of their life.
- Radioactive iodine: This targets the thyroid gland by damaging or destroying the cells that produce thyroid hormone. Treatment usually involves taking 1 dose only in the form of a small capsule.
The relationship between the thyroid and the immune system is complex, and experts do not fully understand it. People with thyroid disease may have weaker immune systems, but it is not clear that this results from having a thyroid condition.
Ongoing research may help doctors better understand thyroid disease, its impact on the immune system, and the relationship between the thyroid and immune function.